This invention relates to methods and apparatus for amplifying a radio-frequency (RF) electrical signal.
In radio communication, amplifiers are commonly used to amplify an RF electrical signal. This may be done before the electrical signal is sent to an antenna to be transmitted as a radio signal, or after an incoming radio signal has been converted to an electrical signal by a radio antenna. An amplifier on a transmit path is commonly referred to as a power amplifier, while an amplifier on a receive path will typically be a low-noise amplifier. Amplifiers may be contained within an integrated radio transceiver module. They can also be provided in standalone integrated-circuit (IC) RF front-end modules.
Standalone front-end devices typically have an input for receiving an outgoing RF electrical signal from a separate radio transceiver device, and an output for providing the amplified outgoing RF signal to an off-chip antenna. They may also have an input for receiving an incoming RF electrical signal from an off-chip antenna, and an output for providing the amplified incoming RF electrical signal to the radio transceiver device. A separate front-end chip may be mounted on a common printed circuit board (PCB) with a radio transceiver chip, or may be integrated with a radio chip in a multi-chip module.
Standalone amplifier devices, or front-end devices, are sometimes used as optional range extenders for increasing the transmission and/or reception range of radio transceiver devices. Front-end devices may provide filtering and switching functions in addition to amplification.
Examples of front-end devices include the “CC2592 2.4-GHz Range Extender” from Texas Instruments™ and the “SKY66112-11 Front-End Module” from Skyworks™. These are both fully-integrated RF front-end module (FEM) for amplifying incoming and outgoing RF signals in the 2.4 GHz band, and may be used for applications such as ZigBee™ and Bluetooth Smart™.
Such devices can provide useful increases in range for radio-on-a-chip devices. However, the applicant has recognised that many conventional RF amplifier devices are not well suited to providing consistent or optimal amplification, especially under changing conditions.
The present invention therefore seeks to provide a better approach.